An electronic computing system that includes one or more central processing units (CPUs), micro-controllers or digital control systems has a power electrical efficiency above 60% at full load when operated at or within full capacity. When the system is idle, in between tasks, or operating at much less than full load (e.g., at 25% of full load), efficiency drops to below 20%. At a power electrical efficiency of 20%, for each ten watts of power the system requires to perform a task, forty watts is wasted. In addition, the system may consume thirty-five watts of power when idle, i.e., while performing no tasks. As electricity resources are becoming increasingly limited and costly, it is important to improve the energy consumption efficiency of computing systems, not only during full load operation, but also to improve efficiency at less than full load, especially when the system is left idle for an extended period of time (e.g., for five minutes, multiple hours or even days).
With the popularity of personal computers, the amount of electrical power that is wasted reaches millions to possibly billions of watts worldwide when computing systems are idling between periods of use. For example, a user may not turn off the power to his computer even when the computer is not in use because the user may not want to wait for the computer to reboot after the computer is turned on. In other words, most users would rather leave their computers on to avoid the time delay for the reboot process than conserve electricity. The same issue applies to other computing devices, appliances and consumer products that include microcontrollers or CPUs.
Therefore, it is desirable to reduce or completely remove power that is provided to an electrically-powered apparatus when the apparatus is not in full use or is left idling for an extended period of time. It is also desirable to anticipate when a user is likely to operate the apparatus such that the apparatus may be ready for immediate user interaction without any delay caused by powering-up the apparatus.